The childhood obstructive sleep apnea syndrome (OSAS) is a common and serious pediatric disease. Previously, we have shown that children have a less collapsible upper airway than adults. This is probably due to differences in neuromotor control of the upper airway. We previously showed that children have a stronger ventilatory drive than adults. Thus, it is probable that children have an increased central nervous system response to stimulation of the upper airway nerves. This may be due to either increased afferent or efferent activity of upper airway reflexes. We hypothesized that children have increased upper airway neuromotor tone secondary to increased upper airway sensory reflexes. In this proposal, we will determine the critical upper airway closing pressure (Pcrit), an objective measure of upper airway collapsibility. The afferent limb of the upper airway response will be compared in children versus adults during sleep, by measuring Pcrit before and after the use of topical anesthesia (lidocaine) to block sensory nerves. This study will advance our understanding of the normal developmental changes in upper airway physiology, thus leading to an improved understanding of the pathophysiology of the childhood obstructive sleep apnea syndrome.